Lighting control system and lighting device

Abstract

The purpose of this disclosure is to provide a lighting control system and lighting device that can dynamically determine the target voltage before lighting in a voltage conversion circuit and prevent lighting abnormalities of the light source. [Solution] The lighting control system of this disclosure comprises a lighting device and a target voltage determination device. The lighting device performs, at the start of lighting the light source, a first rise process which activates a voltage conversion circuit and raises the output voltage of the voltage conversion circuit to the pre-lighting target voltage, a second rise process which raises the output voltage from the pre-lighting target voltage with the constant current circuit activated, and a process which detects the actual output voltage of the voltage conversion circuit when the current flowing to the light source reaches a preset threshold due to the second rise process. The target voltage determination device determines a new pre-lighting target voltage that matches the forward voltage of the light source based on the actual output voltage. The lighting device performs the first rise process based on the new pre-lighting target voltage when the light source is to be lit again.

Description

Technical Field

[0001] The present disclosure relates to a lighting control system and a lighting device.

Background Art

[0002] Patent Document 1 discloses a two-converter type lighting device including a boost circuit and a buck circuit that controls a switching element using the voltage boosted by the boost circuit. In that case, after the output voltage of the boost circuit reaches the pre-lighting target voltage, the switching element of the buck circuit is activated to start bucking. This prevents the switching element from being activated in a state where a sufficient output voltage cannot be obtained immediately after the boost circuit is started, thereby making the operation of the buck circuit unstable.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in a lighting device equipped with a voltage conversion circuit, it is known that the light source lights up abnormally due to the pre-lighting target voltage of the voltage conversion circuit not matching the forward voltage of the light source. For example, when the pre-lighting target voltage is too low with respect to the forward voltage, a sudden current flows through the light source, causing a flash. Conversely, when the pre-lighting target voltage is too high with respect to the forward voltage, an unintended minute current flows through the light source, causing the light source to light up slightly before the circuit responsible for lighting the light source is activated. It is known that there are individual differences in the forward voltage of the light source, and it also varies depending on the usage environment such as temperature and humidity.

[0005] However, the method described in Patent Document 1 has a problem in that the target voltage before ignition is fixed, so the set target voltage before ignition does not necessarily match the forward voltage of the light source, resulting in ignition abnormalities.

[0006] This disclosure aims to provide a lighting control system and lighting device that can dynamically determine the target voltage before lighting in a voltage conversion circuit and prevent lighting abnormalities of the light source, in order to solve the above-mentioned problems. [Means for solving the problem]

[0007] The first aspect of this disclosure is, A constant current circuit having a first switching element whose main terminal is connected in series with the light source, and which maintains a constant current flowing through the light source by adjusting the voltage applied to the control terminal of the first switching element, A voltage conversion circuit having a second switching element, which supplies the output voltage generated by the on / off switching of the second switching element to the light source and the constant current circuit, A lighting device having, Target voltage determination device, Equipped with, The aforementioned lighting device is At the start of the illumination of the aforementioned light source, A first boosting process is performed to activate the voltage conversion circuit by turning the second switching element on and off, thereby raising the output voltage to the target voltage before lighting, The process of starting the constant current circuit by applying a voltage to the control terminal of the first switching element after the output voltage reaches the target voltage before lighting, With the constant current circuit activated, a second boost process is performed to adjust the on-time of the second switching element to raise the output voltage from the target voltage before lighting, A process to detect the actual output voltage, which is the output voltage of the voltage conversion circuit when the current flowing through the light source reaches a preset threshold due to the second rising process, A process of notifying the target voltage determination device of the actual output voltage, It is configured to perform, The target voltage determination device is A decision process to determine a new pre-ignition target voltage for the voltage conversion circuit so as to match the forward voltage of the light source, based on the actual output voltage. A process to notify the lighting device of the newly determined target voltage before lighting, It is configured to perform, The aforementioned lighting device is Preferably, the lighting control system performs the first voltage increase process based on the new pre-ignition target voltage when the light source is turned on for the next time.

[0008] The second aspect is, A constant current circuit having a first switching element whose main terminal is connected in series with the light source, and which maintains a constant current flowing through the light source by adjusting the voltage applied to the control terminal of the first switching element, A voltage conversion circuit having a second switching element, which supplies the output voltage generated by the on / off switching of the second switching element to the light source and the constant current circuit, Control device and It has, The control device is At the start of the illumination of the aforementioned light source, A first boosting process is performed to activate the voltage conversion circuit by turning the second switching element on and off, thereby raising the output voltage to the target voltage before lighting, The process of starting the constant current circuit by applying a voltage to the control terminal of the first switching element after the output voltage reaches the target voltage before lighting, With the constant current circuit activated, a second boost process is performed to adjust the on-time of the second switching element to raise the output voltage from the target voltage before lighting, A process to detect the actual output voltage, which is the output voltage of the voltage conversion circuit when the current flowing through the light source reaches a preset threshold due to the second rising process, A decision process to determine a new pre-ignition target voltage for the voltage conversion circuit so as to match the forward voltage of the light source, based on the actual output voltage. configured to execute, When the light source is started to be lit next time, it is preferable that the lighting device is such that the first rising process is executed based on the new pre-lighting target voltage.

Advantages of the Invention

[0009] In the present disclosure, based on the actual output voltage of the voltage conversion circuit when the light source is lit, a new pre-lighting target voltage is determined so as to match the forward voltage of the light source. When the light source is started to be lit next time, the lighting device activates the voltage conversion circuit based on the new pre-lighting target voltage. Thereby, it is possible to dynamically determine the pre-lighting target voltage of the voltage conversion circuit, and it is possible to provide a lighting control system and a lighting device that can prevent abnormal lighting of the light source. [[ID=~]]

Brief Description of the Drawings

[0010] [Figure 1] It is a circuit diagram of a lighting fixture according to Embodiment 1 of the present disclosure. [Figure 2] It is a diagram showing the junction temperature characteristics of the forward voltage in the LED module of Nichia Chemical Industries, Ltd. [Figure 3] It is a diagram showing the junction temperature characteristics of the forward voltage in the LED module of EVERLIGHT. [Figure 4] It is a diagram for explaining abnormal lighting of a light source that occurs when the pre-lighting target voltage of a voltage conversion circuit is lower than the forward voltage of the light source according to a comparative example of the present disclosure. [Figure 5] It is a diagram for explaining abnormal lighting of a light source that occurs when the pre-lighting target voltage of a voltage conversion circuit is higher than the forward voltage of the light source according to a comparative example of the present disclosure. [Figure 6] It is a diagram for explaining lighting of a light source when the pre-lighting target voltage of a voltage conversion circuit matches the forward voltage of the light source according to Embodiment 1 of the present disclosure. [Figure 7] It is a diagram for explaining a method of determining a new pre-lighting target voltage according to Embodiment 1 of the present disclosure. [Figure 8]This is a diagram for explaining the target voltage before the light is turned off of the voltage conversion circuit and the turning off of the light source according to a modification of Embodiment 1 of the present disclosure.

Embodiments for Carrying Out the Invention

[0011] Embodiments of the present disclosure will be described with reference to the drawings. The same or corresponding components may be denoted by the same reference numerals, and repeated description may be omitted.

[0012] Embodiment 1 FIG. 1 is a circuit diagram of a lighting fixture 100 according to Embodiment 1 of the present disclosure. The lighting fixture 100 includes a light source 11 having one or more LED modules, a lighting device 12, and a dimming interface (I / F) circuit 62.

[0013] The lighting device 12 includes an input filter circuit 1, a voltage conversion circuit (also referred to as a converter circuit) 3, a constant current circuit 4 that maintains a constant current flowing through the light source 11, and a control device 50. [[ID=第十九]]

[0014] An external power supply AC is connected to the input filter circuit 1, and the input filter circuit 1 receives an input voltage from the external power supply AC. The input filter circuit 1 includes a fuse 25 for protecting against overcurrent, an AC capacitor 26, and a diode bridge 27 that full-wave rectifies the AC voltage from the external power supply AC and converts it into a DC voltage. The output of the diode bridge 27 is connected to the voltage conversion circuit 3 on the high potential side and to a grounding terminal (not shown) on the low potential side.

[0015] The voltage conversion circuit 3 includes an isolated flyback circuit including a transformer 14 and a switching element 15, and converts the DC voltage received from the input filter circuit 1 into a voltage suitable for driving the light source 11.

[0016] The voltage conversion circuit 3 includes an input voltage detection unit including a resistor 16 and a resistor 17 connected in series, and divides the input voltage to the voltage conversion circuit 3. The divided value (first voltage) of the resistor 16 and the resistor 17 is detected by the control device 50. Thereby, the control device 50 can detect the input voltage of the external power supply AC.

[0017] Capacitor 10 is connected in parallel with the output of diode bridge 27. This reduces the ripple generated during full-wave rectification by diode bridge 27 and switching by switching element 15, which will be described later. The positive terminal of capacitor 10 is connected to the control power supply generation circuit 19 and one end of the primary side of transformer 14.

[0018] The first main terminal of the switching element 15 is connected in series to the other end of the primary side of the transformer 14.

[0019] The switching element 15 has its first main terminal connected to the transformer 14, its second main terminal connected to the negative terminal and ground terminal of the capacitor 10, and its control terminal connected to the control device 50. The switching element 15 is, for example, a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor). If the switching element 15 is a MOSFET, the first main terminal is the drain terminal, the second main terminal is the source terminal, and the control terminal is the gate terminal.

[0020] The anode of diode 20 is connected to one end of the flyback winding on the secondary side of transformer 14. Diode 20 is provided to transmit a stable voltage to the output side. The positive electrode of electrolytic capacitor 21 is connected to the cathode of diode 20. The negative electrode of electrolytic capacitor 21 is connected to the ground terminal.

[0021] The output voltage detection unit, which includes resistors 22 and 23 connected in series, is connected in parallel with the electrolytic capacitor 21. The voltage division value (second voltage) across resistors 22 and 23 is input to the control device 50. This allows the control device 50 to detect the output voltage (Vo) of the voltage conversion circuit 3.

[0022] The light source 11 has a structure in which multiple LED modules are connected in series. Although multiple LED modules are shown in the figure, only one or more LED modules are required. Furthermore, the light source 11 does not necessarily have to be composed of LEDs; it may also be other light-emitting elements such as organic EL (Electro-Luminescence) or incandescent lamps.

[0023] The constant current circuit 4 is a regulator circuit comprising a switching element 41 connected in series with the light source 11, a resistor 43 for detecting the current (Io) flowing through the light source 11, and a comparator 42. The constant current circuit 4 maintains a constant current supplied to the light source 11 by changing the impedance between the main terminals of the switching element 41.

[0024] The input side of the comparator 42 is connected to the resistor 43 and the control device 50, respectively. The output side of the comparator 42 is connected to the control terminal of the switching element 41. The comparator 42 amplifies the voltage so that the voltage across the resistor 43 matches the voltage supplied by the control device 50, and outputs the resulting voltage, thereby changing the voltage applied to the control terminal of the switching element 41.

[0025] The first main terminal of the switching element 41 is connected in series with the cathode of the light source 11, the second main terminal is connected with the resistor 43, and the control terminal is connected with the comparator 42. The switching element 41 is, for example, a MOSFET. If the switching element 41 is a MOSFET, the first main terminal is the drain terminal, the second main terminal is the source terminal, and the control terminal is the gate terminal. Depending on the voltage applied to the control terminal, the switching element 41 turns the first main terminal and the second main terminal on (short circuit), off (open circuit), or connected with a finite impedance (resistor state). As the impedance between the first main terminal and the second main terminal changes, the current (Io) flowing through the light source 11 also changes.

[0026] One end of resistor 43 is connected to the second main terminal of the switching element 41 and to the input side of comparator 42. The other end of resistor 43 is connected to the ground terminal. A voltage based on the current (Io) flowing through the light source 11 is generated across both ends of resistor 43 by adjusting the impedance of the switching element 41. By using the generated voltage as the input to comparator 42, feedback control can be performed to keep the current (Io) flowing through the light source 11 constant. The voltage generated across both ends of resistor 43 (the fourth voltage) is input to control device 50. This allows control device 50 to detect the current (Io) flowing through the light source 11.

[0027] The voltage detection unit, consisting of resistors 31 and 32 connected in series, has one end connected to the first main terminal of the switching element 41 and the other end connected to the low-potential side of resistor 43. In other words, the voltage detection unit divides the voltage between the main terminals of the switching element 41 (the voltage between the first main terminal and the second main terminal, hereinafter referred to as the terminal voltage), which has been voltage-dropped by resistor 43. The divided voltage value (third voltage) is input to the control device 50. This allows the control device 50 to detect the terminal voltage of the switching element 41.

[0028] The dimming interface (I / F) circuit 62 receives dimming commands or various data from the dimmer 61 and notifies the control device 50.

[0029] The control device 50 can be configured with a known microcontroller (microcomputer) provided as a control device for digital power supplies, or with an arithmetic unit such as a DSP (Digital Signal Processor). The control device 50 includes a central processing unit (CPU) 51, a storage device 52, and a timer 53. The control device 50 receives the first voltage, the second voltage, the third voltage, and the fourth voltage as described above.

[0030] The storage device 52 has volatile or non-volatile memory and stores the calculation program to be executed by the central processing unit 51 and various setting values ​​used in the calculation. The setting values ​​to be stored in the storage device 52 include the target voltage before the voltage conversion circuit 3 lights up. The calculation program here is, for example, a program to operate the voltage conversion circuit 3 in PFC (Power Factor Correction) mode. The storage device 52 can be written to and read by the computer. The central processing unit 51 performs the calculation processing necessary for lighting control based on the digitally converted voltage value.

[0031] The control device 50 receives a dimming command signal from the dimmer 61 via the dimming interface circuit 62. The command from the dimmer 61 includes the content of whether to turn the light source 11 on or off, the dimming value, the fade time, etc. Based on the command content included in the dimming command signal, the control device 50 outputs a PWM signal to turn the light source 11 on or off.

[0032] Furthermore, when the light source 11 is turned on, the control device 50 activates the voltage conversion circuit 3 based on the pre-ignition target voltage stored in the memory device 52. The control device 50 monitors the increase in the current (Io) flowing through the light source 11 when it is turned on by detecting the current flowing through the resistor 43. The control device 50 detects the output voltage (Vo) of the voltage conversion circuit 3 when the current (Io) flowing through the light source 11 reaches a preset threshold and stores it in the memory device 52 as the actual output voltage (Va). In addition, the control device 50 determines a new pre-ignition target voltage (Vn) for the voltage conversion circuit 3 to match the forward voltage of the light source 11 based on the actual output voltage (Va) (determination process).

[0033] Here, the output voltage (Vo) of the voltage conversion circuit 3 is the sum of the forward voltage of the light source 11 and the terminal voltage of the constant current circuit 4. However, since the terminal voltage of the constant current circuit 4 is sufficiently smaller than the forward voltage of the light source 11, the output voltage (Vo) of the voltage conversion circuit 3 can be approximated as the forward voltage of the light source 11. Note that the forward voltage of the light source 11 refers to the minimum voltage required to conduct in the forward direction of the LED module.

[0034] Specifically, the determination process involves determining the new pre-lighting target voltage (Vn) by subtracting a predetermined voltage (Vp) from the actual output voltage (Va) stored in the memory device 52.

[0035] By subtracting a predetermined voltage (Vp) from the actual output voltage (Va) to obtain a new pre-ignition target voltage (Vn), it is possible to prevent the new pre-ignition target voltage (Vn) from being set higher than the forward voltage of the light source 11. Therefore, the dim illumination 80 of the light source 11 can be prevented. It is desirable that the magnitude of the predetermined voltage (Vp) be determined after confirming that it is a voltage that can prevent dim illumination 80.

[0036] Alternatively, the decision process may be a process in which the actual output voltage (Va) is adopted as the new pre-ignition target voltage (Vn). The control device 50 stores the new pre-ignition target voltage (Vn) determined by the decision process in the storage device 52. When the next time the light source 11 is turned on, the control device 50 starts the voltage conversion circuit 3 based on the new pre-ignition target voltage (Vn) stored in the storage device 52.

[0037] Furthermore, from the perspective of eliminating the effects of noise and other factors, the control device 50 detects the actual output voltage (Va) of the voltage conversion circuit 3 each time the light source 11 is turned on, and averages the detection results over multiple times. The control device 50 determines a new pre-lighting target voltage (Vn) by performing a determination process using the average value of the actual output voltage (Va).

[0038] Here, the decision process does not necessarily have to be performed by the lighting device 12, but may also be performed by a target voltage determination device 200 located outside the lighting device 12 in the form of a server, cloud server, control terminal, etc.

[0039] The control device 50 is capable of communicating with the target voltage determination device 200 via wired or wireless communication. The control device 50 notifies the target voltage determination device 200 of lighting device information, including the actual output voltage (Va), and causes the target voltage determination device 200 to determine a new pre-lighting target voltage (Vn) corresponding to the actual output voltage (Va). The control device 50 stores the new pre-lighting target voltage (Vn) determined by the target voltage determination device 200 in the storage device 52.

[0040] The lighting device information that the control device 50 notifies the target voltage determination device 200 is assumed to be the actual output voltage (Va), but it may also include usage environment information such as the operating temperature of the light source 11, the season, temperature, humidity, and time of day at the time of notification. The usage environment information may also be linked to light source information such as the forward voltage of the light source 11, the current (Io) that flowed through the light source 11 when it was lit, and the forward voltage of the light source 11 when it was lit. Furthermore, the lighting device information may also include manufacturing information such as the individual identification number of the light source 11, the individual identification number of the lighting device 12, and the cumulative lighting time of the light source 11.

[0041] The target voltage determination device 200 receives lighting device information from the control device 50 and extracts the actual output voltage (Va) included in the lighting device information. Based on the actual output voltage (Va), the target voltage determination device 200 determines a new pre-lighting target voltage (Vn) that matches the forward voltage of the light source 11. The determination of the new pre-lighting target voltage (Vn) by the target voltage determination device 200 includes the prior determination of a predetermined voltage (Vp) by the target voltage determination device 200.

[0042] Furthermore, the target voltage determination device 200 determines the forward voltage of the light source 11 according to its aging degradation, based on the light source information and manufacturing information, for each individual identification number of the light source 11. In addition, the target voltage determination device 200 determines a new pre-ignition target voltage (Vn) for each individual identification number that matches the determined forward voltage. By taking into account the aging drift of the forward voltage of the light source 11 in this way, the new pre-ignition target voltage (Vn) and the forward voltage of the light source 11 can be made to match even more closely.

[0043] The target voltage determination device 200 is also capable of acquiring information about the operating environment of the light source 11. While it is assumed that the operating environment information is extracted from the lighting device information, the target voltage determination device 200 may generate parameters that can be obtained without referring to the lighting device information, such as season, temperature, and humidity. Based on the operating environment information, the target voltage determination device 200 determines the forward voltage of the light source 11 according to its operating environment. Furthermore, the target voltage determination device 200 determines a new pre-ignition target voltage (Vn) to match the determined forward voltage. In this way, by taking into account the operating environment of the light source 11, the new pre-ignition target voltage (Vn) and the forward voltage of the light source 11 can be further matched.

[0044] Generally, the forward voltage of the light source 11 tends to decrease as the junction temperature increases. Figure 2 shows the junction temperature characteristics of the forward voltage in an LED module from Nichia Corporation. Figure 3 shows the junction temperature characteristics of the forward voltage in an LED module from EVERLIGHT. Assuming a difference of 30°C between winter and summer junction temperatures, Figures 2 and 3 show that the difference in forward voltage between winter and summer is approximately 0.05V per LED module.

[0045] If 100 LED modules are connected in series to form a light source 11, the forward voltage will change by approximately 5V between winter and summer. In other words, if a new target voltage (Vn) set for winter is used in summer, the light source 11 will only dimly light up. Conversely, if a new target voltage (Vn) set for summer is used in winter, the light source 11 will flash. In this disclosure, a new target voltage (Vn) can be set taking into account the operating environment of the light source 11, thereby preventing such abnormal lighting of the light source 11.

[0046] Here, a trained model may be used to determine the new pre-ignition target voltage (Vn). The target voltage determination device 200 inputs the actual output voltage (Va) received from the control device 50 to the trained model, causing the trained model to output a new pre-ignition target voltage (Vn). The trained model is a trained model that has been pre-trained to determine a pre-ignition target voltage (Vn) that matches the forward voltage of the light source 11.

[0047] Alternatively, the trained model may be made to re-learn the forward voltage corresponding to the aging degradation of the light source 11. That is, the target voltage determination device 200 inputs the light source information and manufacturing information into the trained model, causing the trained model to re-learn the aging drift of the forward voltage. This allows the trained model to output a new pre-ignition target voltage (Vn) that takes into account the aging drift of the forward voltage.

[0048] Furthermore, the trained model may be made to re-learn the forward voltage corresponding to the operating environment of the light source 11. That is, the target voltage determination device 200 receives information on the operating environment of the light source 11 and the light source information linked to the operating environment information, thereby causing the trained model to re-learn the forward voltage corresponding to the operating environment of the light source 11. This allows the trained model to output a new pre-ignition target voltage (Vn) that takes into account the operating environment of the light source 11.

[0049] Thus, the lighting device 12 of this disclosure determines a new pre-lighting target voltage (Vn) that matches the forward voltage of the light source 11, based on the actual output voltage (Va) of the voltage conversion circuit 3.

[0050] In this disclosure, the system comprising the lighting device 12 and the target voltage determination device 200 is referred to as a lighting control system.

[0051] The following describes the target voltage before lighting up the voltage conversion circuit 3 and the lighting up of the light source 11.

[0052] <Comparative Example> Here, as a comparative example, we will describe the abnormal lighting of the light source 11 that occurs when the target voltage before lighting of the voltage conversion circuit 3 is lower than (Figure 4) and higher than (Figure 5) the forward voltage of the light source 11.

[0053] Figure 4 illustrates the abnormal lighting of the light source 11 that occurs when the target voltage before lighting of the voltage conversion circuit 3 is lower than the forward voltage of the light source 11, according to a comparative example of this disclosure. The horizontal axis of the figure represents time. The vertical axis represents the output voltage (Vo) of the voltage conversion circuit 3 and the current (Io) flowing through the light source 11.

[0054] 1.Waiting period When the control device 50 receives a dimming command signal indicating that the light will be turned on, it starts timing a first standby time T1 using its built-in timer 53. As the first standby time T1 elapses, the control device 50 turns the switching element 15 of the voltage conversion circuit 3 on and off. This starts the voltage conversion circuit 3, and the output voltage (Vo) rises from 0V to the target voltage before lighting.

[0055] Furthermore, as the first waiting time T1 elapses, the control device 50 starts timing the second waiting time T2. As soon as the second waiting time T2 has elapsed, the control device 50 applies a voltage to the control terminal of the switching element 41 to start the constant current circuit 4.

[0056] In this disclosure, the waiting period is defined as the period from when the control device 50 receives a dimming command signal indicating illumination until the sum of the first waiting period T1 and the second waiting period T2 has elapsed. The second waiting period T2 is provided to stabilize the output voltage (Vo) of the voltage conversion circuit 3 once it has reached the target voltage before illumination. By providing the second waiting period T2, fluctuations in the output voltage (Vo) of the voltage conversion circuit 3 are suppressed from extending into the fade-in period described later, which would cause flashing of the light source 11. This is common not only to the comparative example but also to this disclosure.

[0057] 2. Fade-in period With the constant current circuit 4 activated, the control device 50 adjusts the on-time of the switching element 15 of the voltage conversion circuit 3 so that the third voltage of the constant current circuit 4 reaches the set voltage stored in the memory device 52. As a result, the output voltage (Vo) of the voltage conversion circuit 3 gradually rises from the target voltage before lighting. After the third voltage reaches the set voltage, the control device 50 continues to maintain the output voltage (Vo) of the voltage conversion circuit 3 at a constant value in order to control the third voltage at a constant voltage. The current (Io) flowing through the light source 11 is initially 0A, but rises in accordance with the rise in the output voltage (Vo) of the voltage conversion circuit 3, and after reaching a constant value, it is controlled at a constant current.

[0058] In this disclosure, the period from when the constant current circuit 4 is activated until the current (Io) flowing to the light source 11 becomes constant is referred to as the fade-in period.

[0059] 3. Lighting period When the current (Io) flowing through the light source 11 reaches a constant value, the light output of the light source 11 reaches its maximum, and the light is turned on. In this disclosure, the period during which the current (Io) flowing through the light source 11 is constant is referred to as the "lighting period."

[0060] Here, it is desirable that the current (Io) flowing through the light source 11 rises immediately in response to the rise in the output voltage (Vo) of the voltage conversion circuit 3 during the fade-in period. However, if the target voltage before ignition is lower than the forward voltage of the light source 11, the output voltage (Vo) of the voltage conversion circuit 3 does not reach the forward voltage during the waiting period. Therefore, even if the output voltage (Vo) of the voltage conversion circuit 3 rises from the target voltage before ignition during the fade-in period, it is not possible to immediately supply current to the light source 11.

[0061] If no current flows through the light source 11, the control device 50 increases the on-time of the switching element 15 in an attempt to supply current to the light source 11, causing a sharp increase in the output voltage (Vo) of the voltage conversion circuit 3. When the output voltage (Vo) surges and exceeds the forward voltage of the light source 11, a large current (Io) suddenly flows through the light source 11, causing it to light up with a high light output. This is the flash 70 of the light source 11. The magnitude of the flash 70 increases as the target voltage before lighting is lower than the forward voltage of the light source 11.

[0062] Figure 5 illustrates the abnormal lighting of the light source 11 that occurs when the target voltage before lighting of the voltage conversion circuit 3 is higher than the forward voltage of the light source 11, according to a comparative example of the present disclosure. Similar to Figure 4, the horizontal axis of the figure represents time. The vertical axis represents the output voltage (Vo) of the voltage conversion circuit 3 and the current (Io) flowing through the light source 11.

[0063] 1.Waiting period When the control device 50 receives a dimming command signal indicating that the light will be turned on, it starts timing the first waiting time T1. As the first waiting time T1 elapses, the control device 50 activates the voltage conversion circuit 3, as described in Figure 4. As a result, during the second waiting time T2, the output voltage (Vo) rises from 0V to the target voltage before turning on the light.

[0064] If the pre-ignition target voltage is higher than the forward voltage of the light source 11, a high voltage is applied between the light source 11 and the main terminal of the constant current circuit 4 while the output voltage (Vo) rises to the pre-ignition target voltage. In this case, an unintended circuit is formed in which current from the light source 11 flows through resistors 31 and 32, and a small current continues to flow through the light source 11 during the second waiting time T2. As a result, the light source 11 is dimly lit even before the constant current circuit 4, which is supposed to light up the light source 11, is activated. The light output of the light source 11 in this dim lighting 80 increases as the pre-ignition target voltage is higher than the forward voltage of the light source 11.

[0065] It is also possible to shorten the second standby time T2 so that the user does not notice the faint illumination 80. However, the second standby time T2 is necessary to stabilize the output voltage (Vo) of the voltage conversion circuit 3, so it cannot be shortened to an extreme degree.

[0066] 2. Fade-in period With the constant current circuit 4 activated, the control device 50 gradually increases the output voltage (Vo) of the voltage conversion circuit 3 from the pre-ignition target voltage, as described in Figure 4, to bring the third voltage to the set voltage. After the third voltage reaches the set voltage, the control device 50 maintains the output voltage (Vo) of the voltage conversion circuit 3 at a constant value in order to control the third voltage at a constant voltage. At the start of the fade-in period, a small current continues to flow through the light source 11, but as the output voltage (Vo) of the voltage conversion circuit 3 rises, the current (Io) flowing through the light source 11 also rises, and constant current control is applied when it reaches a certain value.

[0067] 3. Lighting period Similar to the explanation in Figure 4, when the current (Io) flowing through the light source 11 reaches a constant value, the light output of the light source 11 reaches its maximum, and the light is turned on.

[0068] As explained above, in the comparative example lighting device 12, the pre-ignition target voltage of the voltage conversion circuit 3 does not match the forward voltage of the light source 11, resulting in a lighting abnormality in the light source 11. Furthermore, it is known that there are individual differences in the forward voltage of the light source 11, and that it fluctuates depending on the operating environment such as temperature and humidity. Therefore, when the pre-ignition target voltage is fixedly set for the lighting device 12, the pre-ignition target voltage does not necessarily match the forward voltage of the light source 11, resulting in the problem of lighting abnormalities occurring.

[0069] <This Disclosure> In this disclosure, the voltage conversion circuit 3 is activated based on a new pre-ignition target voltage (Vn). The new pre-ignition target voltage (Vn) is determined to match the forward voltage of the light source 11.

[0070] Figure 6 illustrates the illumination of the light source 11 according to Embodiment 1 of this disclosure, when the target voltage before illumination of the voltage conversion circuit 3 matches the forward voltage of the light source 11. The horizontal axis of the figure represents time. The vertical axis represents the output voltage (Vo) of the voltage conversion circuit 3 and the current (Io) flowing through the light source 11.

[0071] 1.Waiting period When the control device 50 receives a dimming command signal indicating that the light will be turned on, it starts timing a first waiting time T1. As the first waiting time T1 elapses, the control device 50 activates the voltage conversion circuit 3 by turning the switching element 15 of the voltage conversion circuit 3 on and off, and raises the output voltage (Vo) from 0V to a new pre-lighting target voltage (Vn) (first boosting process).

[0072] Furthermore, as the first waiting time T1 elapses, the control device 50 starts timing the second waiting time T2. As soon as the second waiting time T2 has elapsed, the control device 50 starts the constant current circuit 4 in the same manner as described in Figure 4.

[0073] 2. Fade-in period With the constant current circuit 4 activated, the control device 50 gradually increases the output voltage (Vo) of the voltage conversion circuit 3 from the pre-ignition target voltage, as described in Figure 4, to bring the third voltage to the set voltage (second rise process). After the third voltage reaches the set voltage, the control device 50 maintains the output voltage (Vo) of the voltage conversion circuit 3 at a constant value in order to control the third voltage at a constant voltage. The current (Io) flowing through the light source 11 is initially 0A, but increases in accordance with the rise in the output voltage (Vo) of the voltage conversion circuit 3, and after reaching a constant value, it is controlled at a constant current.

[0074] 3. Lighting period Similar to the explanation in Figure 4, when the current (Io) flowing through the light source 11 reaches a constant value, the light output of the light source 11 reaches its maximum, and the light is turned on.

[0075] In this disclosure, since the new pre-ignition target voltage (Vn) matches the forward voltage of the light source 11, abnormal illumination of the light source 11, such as flashing 70 and dim illumination 80, can be prevented.

[0076] Figure 7 illustrates a method for determining a new pre-ignition target voltage (Vn) according to Embodiment 1 of this disclosure. The process by which the control device 50 activates the voltage conversion circuit 3 and the constant current circuit 4 is the same as in Figure 6, so its explanation is omitted.

[0077] The control device 50 detects the output voltage (Vo) of the voltage conversion circuit 3 when the current (Io) flowing through the light source 11 reaches a preset threshold during the second boosting process, and sets this as the actual output voltage (Va). Furthermore, based on the actual output voltage (Va), the control device 50 determines a new pre-ignition target voltage (Vn) for the voltage conversion circuit 3 to match the forward voltage of the light source 11. Here, the voltage obtained by subtracting a predetermined voltage (Vp) from the actual output voltage (Va) is determined as the new pre-ignition target voltage (Vn). When the light source 11 is to be turned on again, the control device 50 executes the first boosting process based on the new pre-ignition target voltage (Vn). This prevents the light source 11 from malfunctioning when it is turned on again.

[0078] As described above, this disclosure provides a lighting device 12 and a lighting control system that can dynamically determine the target voltage before lighting the voltage conversion circuit 3 and prevent lighting abnormalities of the light source 11.

[0079] <Variation 1> Figure 8 illustrates the target voltage before turning off the light in the voltage conversion circuit 3 and the turning off of the light source 11 in a modified example of Embodiment 1 of this disclosure. In the lighting device 12 of this embodiment, the power supply for the control device 50 is easily secured by constant voltage control of the voltage conversion circuit 3. On the other hand, if the output voltage (Vo) is increased too much, a problem arises in which current flows to the light source 11 even while it is being turned off, causing the light source 11 to dimly light up.

[0080] In this embodiment, the control device 50 stores the forward voltage of the light source 11 as the actual output voltage (Va) in the memory device 52. This can be used to prevent faint illumination when the light source 11 is turned off. Specifically, during the fade-out period, the control device 50 adjusts the on-time of the switching element 15 to lower the output voltage (Vo) of the voltage conversion circuit 3 to the target voltage before turning off. The target voltage before turning off is lower than the actual output voltage (Va), and is effectively below the forward voltage of the light source 11, so no current flows to the light source 11. This ensures that the light source 11 is reliably turned off.

[0081] This disclosure is not limited to the embodiments described above, and various modifications can be made during implementation without departing from its essence. Furthermore, each embodiment and its modifications may be combined as appropriate, and in that case, the combined effects can be obtained. [Explanation of symbols]

[0082] 1: Input filter circuit, 3: Voltage conversion circuit, 4: Constant current circuit, 10: Capacitor, 11: Light source, 12: Lighting device, 14: Transformer, 15: Switching element (second switching element), 16: Resistor, 17: Resistor, 19: Control power generation circuit, 20: Diode, 21: Electrolytic capacitor, 22: Resistor, 23: Resistor, 25: Fuse, 26: Capacitor, 27: Diode bridge, 31: Resistor, 32: Resistor, 41: Switching element (first switching element), 42: Comparator, 43: Resistor, 50: Control device, 51: Central processing unit, 52: Memory device, 53: Timer, 61: Dimmer, 62: Dimming interface circuit, 70: Flash, 80: Dimming, 100: Lighting fixture, 200: Target voltage determination device

Claims

1. A constant current circuit having a first switching element whose main terminal is connected in series with the light source, and which maintains a constant current flowing through the light source by adjusting the voltage applied to the control terminal of the first switching element, A voltage conversion circuit having a second switching element, which supplies the output voltage generated by the on / off switching of the second switching element to the light source and the constant current circuit, A lighting device having, Target voltage determination device, Equipped with, The aforementioned lighting device is At the start of the illumination of the aforementioned light source, A first boosting process is performed to activate the voltage conversion circuit by turning the second switching element on and off, thereby raising the output voltage to the target voltage before lighting, The process of starting the constant current circuit by applying a voltage to the control terminal of the first switching element after the output voltage reaches the target voltage before lighting, With the constant current circuit activated, a second boosting process is performed to adjust the on-time of the second switching element to raise the output voltage from the target voltage before lighting, A process to detect the actual output voltage, which is the output voltage of the voltage conversion circuit when the current flowing through the light source reaches a preset threshold due to the second rising process, A process of notifying the target voltage determination device of the actual output voltage, It is configured to perform, The target voltage determination device is A decision process to determine a new pre-ignition target voltage for the voltage conversion circuit so as to match the forward voltage of the light source, based on the actual output voltage. A process to notify the lighting device of the newly determined target voltage before lighting, It is configured to perform, The aforementioned lighting device is A lighting control system that, when the light source is turned on for the next time, performs the first voltage increase process based on the new pre-ignition target voltage.

2. The target voltage determination device is A process for acquiring information on the operating environment of the aforementioned light source, Based on the aforementioned usage environment information, a process is performed to determine the forward voltage corresponding to the usage environment of the light source, Further execution, The lighting control system according to claim 1, wherein the determination process is a process of determining the new pre-lighting target voltage to match the determined forward voltage.

3. The target voltage determination device further performs a process to determine the forward voltage according to the aging degradation of the light source, The lighting control system according to claim 1 or 2, wherein the determination process is a process of determining the new pre-lighting target voltage to match the determined forward voltage.

4. The target voltage determination device further performs a process to obtain the individual identification number of the light source, The forward voltage corresponding to the aging degradation of the light source is determined for each individual identification number. In the determination process, the new pre-lighting target voltage is determined for each individual identification number, as described in claim 3, for the lighting control system.

5. The lighting control system according to claim 1, wherein the determination process is a process of determining the voltage obtained by subtracting a predetermined voltage from the actual output voltage as the new target voltage before lighting.

6. The aforementioned lighting device is Equipped with additional storage, A process to store the actual output voltage in the memory device, At the start of the light source being switched off, the process of adjusting the on-time of the second switching element to lower the output voltage of the voltage conversion circuit to a voltage lower than the actual output voltage stored in the memory device, The lighting control system according to claim 1, further comprising the following steps.

7. A constant current circuit having a first switching element whose main terminal is connected in series with the light source, and which maintains a constant current flowing through the light source by adjusting the voltage applied to the control terminal of the first switching element, A voltage conversion circuit having a second switching element, which supplies the output voltage generated by the on / off switching of the second switching element to the light source and the constant current circuit, Control device and It has, The control device is At the start of the illumination of the aforementioned light source, A first boosting process is performed to activate the voltage conversion circuit by turning the second switching element on and off, thereby raising the output voltage to the target voltage before lighting, The process of starting the constant current circuit by applying a voltage to the control terminal of the first switching element after the output voltage reaches the target voltage before lighting, With the constant current circuit activated, a second boosting process is performed to adjust the on-time of the second switching element to raise the output voltage from the target voltage before lighting, A process to detect the actual output voltage, which is the output voltage of the voltage conversion circuit when the current flowing through the light source reaches a preset threshold due to the second rising process, A decision process to determine a new pre-ignition target voltage for the voltage conversion circuit so as to match the forward voltage of the light source, based on the actual output voltage. It is configured to perform, A lighting device in which, when the light source is to be turned on again, the first voltage increase process is performed based on the new pre-lighting target voltage.

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